Cotyledonary Storage Proteins in Pisum sativum. IV. Effects of Sulfur, Phosphorus, Potassium and Magnesium Deficiencies

Abstract

The quantitative and qualitative effects of deficiency of S, P, K or Mg on the cotyledonary proteins of pea seeds have been studied using chemical, immunological and electrophoretic techniques.

Deficiency of S, P or K causes characteristic and consistent changes in the proportions of certain proteins both outside and inside protein bodies of mature seeds. Amongst the storage proteins in the protein bodies, S deficiency results in a relative decrease in legumin and in vicilin peak 3, accompanied by a relative increase in the predominant vicilin, peak 4. A quantitatively major cotyledonary protein of unknown function, located outside protein bodies and consisting of 22- kdalton polypeptides, is decreased by S deficiency. Deficiencies of P or K cause an increase in the quantitatively minor vicilin peak 3 and also a marked relative increase in legumin. Mg deficiency has little effect on the proportions of the storage proteins.

The degree of nutrient deficiency is reflected in seed and plant yields. Total N and trichloroacetic acid (TCA)-insoluble N and the contents of some other mineral elements in the seed are given. A 10-fold increase in sulfur supply above the optimum for yield did not increase N or S in the TCA- insoluble fraction.